By employing aerobic oxidation to aldehydes as a more effective alcohol activation strategy, ligand-free copper catalysts were found to be superior catalysts than other metals in aerobic dehydrative β-alkylation of secondary alcohols and α-alkylation of methyl ketones using alcohols as the green alkylating reagents. Based on our mechanistic studies and also supported by the literature, we deduc...

Alkylation of beta-amino ester enolates proceeds with high diastereoselectivity. Single crystal, powder, and solution X-ray diffraction studies of the enolate show that the racemic enolate forms prismatic hexamers. 6Li NMR spectroscopic studies on partially racemic enolates reveal complex mixtures of homo- and heterochiral hexamers. An implicit fit of the aggregate populations to the Boltzmann ...

cate that cellular deoxyribonucleic acid (DNA) might be the primary and perhaps the critical site of alkylation by cytotoxic alkylating agents (21). The biologic systems used in most of these investigations, however, have not permitted a direct correlation between alkylation of DNA and the observed biologic effects; that is, there is a lack of evidence whether alkylation of DNA is essential to ...

An efficient diastereo- and enantioselective Friedel-Crafts alkylation of indoles with 3-nitro-2H-chromenes catalyzed by diphenylamine-linked bis(oxazoline) and bis(thiazoline) Zn(II) complexes has been developed. This asymmetric Friedel-Crafts alkylation led to medicinally privileged indolyl(nitro)chromans in good yields with high enantioselectivities (up to 95% ee) and diastereoselectivities ...

The effects of steroid-induced modifications of chromatin structure on the extent and sites of chloroethylnitrosourea binding to chromatin were studied using log-phase HeLa cells. The cells were exposed to 0.1 to 2.0 microM hydrocortisone for 22 hr; this resulted in depressed DNA synthesis while transcriptional activity was stimulated. Hydrocortisone had no effect upon cellular or nuclear uptak...

The objective of these experiments was to understand the mechanism of cocarcinogenicity of asbestos and polycyclic aromatic hydrocarbons. Benzo(a)pyrene [B(a)P] was coated onto crocidolite or chrysotile asbestos fibers, resuspended in serum-free medium, and added to cultures of hamster tracheal epithelial cells. The fibers markedly enhanced cell uptake of B(a)P. Although considerable metabolism...

This work details the development of ruthenium(II) catalysts for the enantioselective alkylation of chiral racemic secondary phosphines. The reactions proceed through the intermediacy of nucleophilic phosphido species, which have low barriers to pyramidal inversion; this allows for a dynamic kinetic asymmetric alkylation. The initially discovered [((R)-iPr-PHOX)(2)Ru(H)][BPh(4)] (6) catalyst wa...

An improved strategy for the synthesis of 2'-O-methyl-guanosine (6) and 2'-MOE-guanosine (8) is reported. The regioselectivity of the alkylation was attained using a novel silicon-based protecting group, methylene-bis (diisopropyl-silylchloride) (MDPSCl2, 2). The alkylation proceeded in a chemoselective manner using NaHMDS as the base and MeCl or MOE-Br as the appropriate electrophiles.

Highly congested vicinal stereocenters comprised of tertiary and all-carbon quaternary centers were generated via Ir-catalyzed asymmetric allylic alkylation of β-ketoesters. These catalytic reactions proceed in excellent yields with a broad scope on either reaction partner and with outstanding regio-, diastereo-, and enantiocontrol. Implementation of a subsequent Pd-catalyzed alkylation affords...

[reaction: see text] The diastereoselective alkylation of glycolate oxazolidinones has been demonstrated as a method for the enantioselective preparation of alpha-alkoxy carboxylic acid derivatives and selectively protected 1,2-diols. Various protecting groups on the glycolate hydroxyl and multiple substitution patterns on allylic iodides are tolerated in the alkylation. Yields for the alkylati...